The Urban Dictionary T-Shirt

Well, it orginally meant a girl who can't keep her legs closed. It still does, but also now girls call each other sluts as a result of jealousy just because the girl who's being called a slut is either a) prettier and gets more attention from guys and people in general or b) she has something the girl calling her a slut doesn't.

Girls call me a slut because they know I'll get more sex in a week than they'll get in their lives

The Urban Dictionary T-Shirt

A person, usually female, who has dissociated themselves from their body and who has stripped the sexual act of any meaning and significance by engaging in frequent sexual encounters indiscriminantly with multiple partners without regard to the identity of and relationship with their partners.

The Urban Dictionary T-Shirt

Supposedly means a person, generally a woman, who may have slept with a generally large amount of people. Most of the time the person using this term is not actually saying it to the "slut" in question, and they normally do not actually know if the "slut" they are talking about is even a "slut" at all.